Analysis by: Kiyoshi Obuchi
ALIASES:

Trojan:Win32/Tiggre!rfn (Microsoft); a variant of Win32/Agent.TDX (ESSET)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

  TECHNICAL DETAILS

File Size: 1,435,136 bytes
File Type: EXE
File Compression: UPX
Memory Resident: No
Initial Samples Received Date: 08 Jun 2018

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Trojan creates the following folders:

  • %Windows%\rss

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

Autostart Technique

This Trojan adds and runs the following services:

  • WinDefender

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
TestApp
ServiceVersion = "0.5"

Download Routine

This Trojan connects to the following website(s) to download and execute a malicious file:

  • http://{BLOCKED}pdata.johnywalkerup.com/app.exe

It saves the files it downloads using the following names:

  • %Windows%\rss\crss.exe

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

Other Details

This Trojan does the following:

  • Executes the following commands to set the permission of the created service:
    • sc sdset WinDefender D:(A;;CCLCSWRPWPDTLOCRRC;;;SY)(A;;CCDCLCSWRPLOCRSDRCWDWO;;;BA)(D;;WPDT;;;BA)(A;;CCLCSWLOCRRC;;;IU)(A;;CCLCSWLOCRRC;;;SU)S:(AU;FA;CCDCLCSWRPWPDTLOCRSDRCWDWO;;;WD)
  • The registry key: "HKEY_CURRENT_USER\Software\Microsoft\TestApp" must exist for successful execution
  • If the initial file name and file path is not %Windows%\windefender.exe, it will copy and run itself in the following file path:
    • %Windows%\windefender.exe

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.348.06
FIRST VSAPI PATTERN DATE: 08 Jun 2018
VSAPI OPR PATTERN File: 14.349.00
VSAPI OPR PATTERN Date: 09 Jun 2018

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode, and then delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • Windefender

Step 4

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\TestApp
    • ServiceVersion = "0.5"

Step 5

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %Windows%\rss

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_GODEFWIN.A. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.


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